Field of the Invention
The present invention relates to an evaluation apparatus that evaluates electrical characteristics of an object subject to measurement that is a to-be-measured object, and to an evaluation method.
Description of the Background Art
Evaluation apparatuses that evaluate electrical characteristics of a to-be-measured object, such as a semiconductor device that is a semiconductor wafer or semiconductor chips diced from the semiconductor wafer have been known. When evaluating the electrical characteristics, the evaluation apparatuses bring, for example, by vacuum suction, an installation surface of the to-be-measured object in contact with a placed surface of a chuck stage to fix the installation surface, and then bring a probe that transmits and receives electrical signals in contact with an electrode disposed on a part of a non-installation surface of the to-be-measured object. When the to-be-measured object is a semiconductor device with a vertical structure which applies a high current in a vertical direction, that is, in an off-plane direction, a chuck stage equipped with an electrode on its placed surface is used. In such evaluation apparatuses, the number of pins has long been increased to meet the demand for application of a high current and a high voltage.
When the to-be-measured object is a semiconductor device with the vertical structure that is formed into a chip, a potential difference between an electrode disposed on a part of a non-installation surface of the semiconductor device and an area closer to the chuck stage that has the same potential as that of the chuck stage may cause a partial discharge phenomenon during the evaluation. This partial discharge causes a partial breakage or a malfunction in the semiconductor device. The partial discharge may occur between probes having a potential difference or between a probe and another electrode having a potential difference with the probe.
If a semiconductor device in which the partial discharge has occurred is sent to subsequent processes as a conforming item as it is, it is very difficult to screen out such a semiconductor device in the subsequent processes. Thus, it is desirable to take a measure against a malfunction caused by the partial discharge through prevention of the partial discharge. Accordingly, various techniques for preventing the partial discharge have been proposed (for example, Japanese Patent Application Laid-Open No. 2011-252792 (hereinafter referred to as Patent Document 1) and Japanese Patent Application Laid-Open No. 2015-35577 (hereinafter referred to as Patent Document 2)).
Under the technique disclosed by Patent Document 1, a to-be-measured object is placed in a sealed pressure vessel and is evaluated with application of pressure to the pressure vessel to prevent the discharge occurring while the to-be-measured object is being tested with a high voltage. Under the technique disclosed by Patent Document 2, a device in a wafer is inspected with application of pressure to a component in a non-sealing state without using a sealed pressure vessel to prevent the discharge.
However, since a foreign substance present on the to-be-measured object in the evaluation may create a discharge path through the foreign substance under the techniques of both Patent Documents 1 and 2, the likelihood of a discharge preventing effect may be slim.